Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
Yawns are more contagious among people with closer relationships.
163
Enamel is hardest substance in the human body.
61
The human body contains over a billion miles of DNA.
147
After age 30, the brain begins to lose about 50,000 neurons per day - shrinking the brain .25% each year.
55
It takes about 20 seconds for a red blood cell to circle the whole body.
102
When you take a step, you are using up to 200 muscles.
886
Poor eyesight (myopia) is associated with higher IQ.
232